DE 10 2007 036 824 A1 has disclosed a generic flap arrangement having a housing and having a flap, which is arranged in the housing, for regulating an air flow in the housing, wherein the flap has a flap main body which has a front side, arranged on the air inflow side at least in an operating state, and a rear side, arranged on a side averted from the flow. Here, on the rear side of the flap main body, there is arranged an air-guiding element which extends at an oblique angle with respect to the rear side of the flap main body. In this way, it is sought in particular to be able to at least minimize an unpleasant whistling noise upon opening and closing of the flap.
A further flap arrangement having a flap is known from EP 1 783 409 A1.
In the use of flaps which are mounted in single-limb configuration, in particular in air conditioning systems of motor vehicles, it is initially the case during the opening of said flaps that a narrow gap is formed through which a high air flow rate is diverted in the manner of a funnel, so to speak. If a rectilinear obstruction, for example a groove of a fitted duct or an edge, is situated closely downstream of said gap and transversely with respect to the inflow direction, an unpleasant whistling noise can occur. Since such obstructions are however, in part, unavoidable, the escape of air from the gap must be impeded. This partial impedance must however again have no adverse effects in terms of acoustics or air flow rate when the flap is fully open. A disadvantage in the case of the flap arrangements known from the prior art is however that their capability for reducing the whistling noises is only inadequate, because they are situated too far away from the air gap itself during the opening of the flap.